Ortak Dersler Bölümü

Permanent URI for this communityhttps://hdl.handle.net/20.500.12416/1817

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Forecasting The Natural Gas Demand At New Locations A Case Study For Turkey
(2005) Türker Bayrak, Özlem; Köksal, Gülser; Okandan, Ender; 56416
Sample design and allocation for random digit dialling
(Springer, 2005) Ayhan, H. Öztaş; Islam, M. Qamarul
Sample design and sample allocation methods are developed for random digit dialling in household telephone surveys. The proposed method is based on a two-way stratification of telephone numbers. A weighted probability proportional to size sample allocation technique is used, with auxiliary variables about the telephone coverage rates, within local telephone exchanges of each substrata. This makes the sampling design nearly "self-weighting" in residential numbers when the prior information is well assigned. A computer program generates random numbers for the local areas within the existing phone capacities. A simulation study has shown greater sample allocation gain by the weighted probabilities proportional to size measures over other sample allocation methods. The amount of dialling required to obtain the sample is less than for proportional allocation. A decrease is also observed on the gain in sample allocation for some methods through the increasing sample sizes.
Spam mail filtering using Bayesian classifier and heuristics
(2006) Eş, Sinan; Hassanpour, Reza; Hassanpour, Reza; 56475
Commercials and virus infected files transferred by electronic mails (e-mail) have been a main source of time and resource loss during the past decade and email filtering as a binary text classification problem has attracted the attention of many researchers recently. In this study, we have tried to find a filtering solution which is able to automatically classify emails into spam and legitimate categories. In order to automatically and efficiently classify emails as spam or legitimate we took advantage of some Bayesian stochastic algorithms and machine learning based heuristic methods. Our approach includes some novel ideas from Information Retrieval.
Inter-laboratory comparison scheme for fuel sector, LABKAR in Turkey
(Springer, 2009) Bayrak, Özlem Türker; Okandan, Ender; Üçkardeş, Hale; 56416
Fuel sector is one of the powerful sectors in Turkish industry. The implementation of a new law for regulating the fuel sector had enforced the quality control of fuels sold to public. This resulted in several accredited fuel-testing laboratories to emerge. Thus, a scheme to evaluate their proficiency in measurements became an important requirement. The inter-laboratory comparison scheme LABKAR for gasoline, diesel oil, LPG, lubricating oil and biodiesel samples have evolved to fulfill this need. In this paper, LABKAR is introduced; the results obtained from the program are analyzed and discussed. The kernel densities of the participants' results show that the use of robust mean as a consensus value is appropriate for fuel samples. Although the number of rounds is not enough to derive strict conclusions, it is seen that the performance of the scheme based on the standard deviations and coefficient of variations is improving in each round. It has been observed that the number of laboratories receiving "action" or "warning" is decreasing, which indicates that they are benefiting from the scheme.
Classification Models Based On Tanaka's Fuzzy Linear Regression Approach: the Case of Customer Satisfaction Modeling
(IOS Press, 2010) Bayrak, Özlem Türker; 56416
Fuzzy linear regression (FLR) approaches are widely used for modeling relations between variables that involve human judgments, qualitative and imprecise data. Tanaka's FLR analysis is the first one developed and widely used for this purpose. However, this method is not appropriate for classification problems, because it can only handle continuous type dependent variables rather than categorical. In this study, we propose three alternative approaches for building classification models, for a customer satisfaction survey data, based on Tanaka's FLR approach. In these models, we aim to reflect both random and fuzzy types of uncertainties in the data in different ways, and compare their performances using several classification performance measures. Thus, this study contributes to the field of fuzzy classification by developing Tanaka based classification models.
Intellectual freedom and libraries: A quantitative discourse analysis
(2010) Darvish, Hamid; 19489
United Nation published Human Rights Declaration in 1948. The most important part of the Human Right Declaration is that, everyone has the right to search and receive information at any time. To this respect, libraries play a significant task in disseminating information (Knowledge) to each individual. An exploratory approach is applied to selected discourses from organizations such as IFLA (International Federation of Library Associations and Institutions), ALA (American Library Association) and TLA (Turkish Librarians’ Association) to find out if there is a coherent relation among texts, by applying Latent Semantic Analysis (LSA) technique. Results yield that there existed a positive relation among discourses.
Çankaya Üniversitesi, Ortak Dersler Bölümü, Eğitim Teknolojileri Bilim Dalı
(2011) Akkoyunlu, Buket; Yılmaz Soylu, Meryem; 8539
Bu çalışmanın amacı, ilköğretim 7. ve 8. sınıf öğrencilerinin, sosyal iletişim ağlarında (Facebook, Youtube, Myspace, Twitter, Blogs) Türkçenin yanlış kullanımını belirlemeye yönelik yaptıkları projeleri inceleyerek öğrencilerin Türkçenin korunmasına dönük çözüm önerilerini ortaya koymaktır. Araştırmada, nitel araştırma yöntemlerinden durum çalışması yöntemi kullanılmıştır). Çalışmada 7. ve 8. sınıf öğrencileri sosyal iletişim ağlarındaki (Facebook, Youtube, Myspace, Twitter, Blogs) yazışmalarda Türkçenin (dilin) nasıl kullanıldığı incelenmiş, yanlışları tespit etmiş ve dilin doğru kullanılmasına dönük çözüm önerileri sunmuşlardır. Öğrenciler, sosyal iletişim ağlarında Türkçe kullanım yanlışlarını ses özelikleri ile ilgili yanlış kullanımlar, sözcüklerle ilgili yanlış kullanımlar, cümleler ile ilgili yanlış kullanımlar, yazım özellikleriyle ilgili yanlış kullanımlar boyutlarında değerlendirmişlerdir. Öğrencilerin açık uçlu sorulara verdikleri yanıtları ve sürece dönük yansımalarını incelemek amacıyla da içerik analizi yapılmış ve temalar altında gruplanmıştır. Sonuç olarak öğrencilerin sürece ilişkin yansımaları, araştırmacıları 3 ana temaya ulaştırmıştır. Bunlar; bireysel adımlar, toplumsal adımlar ve kurumsal adımlar olarak sınıflandırılmış, öğrencilerin sürece ilişkin yansımaları bu üç başlık altında incelenmiştir. Raporlar incelendiğinde, öğrencilerin öğrenciler dili korumak için kendilerinin yapabileceklerinden, toplumsal olarak yapılabileceklerden ve resmi ve özel kurumların Türkçeyi korumak için yapabileceklerinden söz ettikleri görülmektedir.
Kimyasal bağlar konusunda tasarlanan türetimci çoklu ortamın kalıcılık ve tutuma etkisi ile öğretmen adaylarının ortama ilişkin görüşleri
(2012) Akkoyunlu, Buket; Yılmaz, Ayhan; Akkoyunlu, Buket; 8539
Electricity Price Modelling for Turkey
(Springer-Verlag Berlin, 2012) Yıldırım, Miray Hanım; Bayrak, Özlem Türker; Weber, Gerhard Wilhelm; Özmen, Ayşe; 56416
This paper presents customized models to predict next-day's electricity price in short-term periods for Turkey's electricity market. Turkey's electricity market is evolving from a centralized approach to a competitive market. Fluctuations in the electricity consumption show that there are three periods; day, peak, and night. The approach proposed here is based on robust and continuous optimization techniques, which ensures achieving the optimum electricity price to minimize error in periodic price prediction. Commonly, next-day's electricity prices are forecasted by using time series models, specifically dynamic regression model. Therefore electricity price prediction performance was compared with dynamic regression. Numerical results show that CMARS and RCMARS predicts the prices with 30% less error compared to dynamic regression.
Temperature-dependent absorption edge and photoconductivity of Tl 2In2S3Se layered single crystals
(2013) Güler, İpek; Ambrico, M.; Ligonzo, T.; Gasanly, N.M.; 101531
Temperature variation of indirect band gap of Tl2In 2S3Se layered single crystals were obtained by means of absorption and photoconductivity measurements. The temperature coefficient of -7.1 × 10-4 eV/K from absorption measurements in the temperature range of 10-300 K in the wavelength range of 520-1100 nm and -5.0 × 10-4 eV/K from PC measurements in the temperature range of 132-291 K in the wavelength range of 443-620 nm upon supplying voltage V = 80 V were obtained. From the analysis of dark conductivity measurements in the temperature range of 150-300 K, conductivity activation energy was obtained as 0.51 eV above 242 K. The degree of the disorder, the density of localized states near Fermi level, the average hopping distance and average hopping energy of Tl2In2S3Se crystals were found as, 1.9 × 105 K, Nf = 4 × 1020 cm -3eV-1, 29.1 Å and 24.2 meV in the temperature range of 171-237 K, respectively. Activation energy of hopping conductivity at T = 171 K was obtained as 41.3 meV and the concentration of trapping states was found as 1.6 × 1019 cm-3.
SAYISAL YETKiNLiK
(2013) Akkoyunlu, Buket; 8539
Say1sal teknolojiler hlZia geliJmektedir. Bilgi patlamas1 karJlsmda bireylerlkurumlar say1sal yetkinlige sahip olmabd1r. Say1sal olarak yetkin ve uyumlu hale gelmek, say1sal teknoloji/erin potansiyel/erinden en iyi Jekilde faydalanmak anlamma gelmektedir. Bu railJmada, yetkinlik si!zciigii, bireylerin kendileri i9in i!nem/i alan §eylerin farlanda olma ve i!nemli alan iJ[eri yapma; bireylerin kendi yaJamlan ve revreleri iizerinde kontrol sahibi alma yetisi anlammda kul/amlmaktadlY. Say1sal teknolojiler, bireylerin bilgi toplumunda katlilmcl rol oynamalanm ve kendilerini ifade etmek irin yeni beceriler edinmelerini zorunlu lalmlJ ve hatta onlara reJitli olanaklar saglamlJtlY. BUJka bir deyiJle, say1sal teknoloji/ere sahip alma ve kullanabi/menin i!tesinde say1sal yetkinlik Onem kazanmz§tzr. Ancak, sayzsal teknolojilerin kullammz sadece eri§im ve kullamm boyutuyla ele almmamabd r. Say1sal yetkinlik, say1sal teknolojileri biiyiik miktarlarda iiretilmekte alan bilginin irinden ihtiyar duyulan bilgiye eriJme arac1 olarak kullamp, ulaJlian bilgiyi anlama, degerlendirme ve bilgi iiretme becerilerini de irermektedir. Bireylere say1sal yetkinlik kazandmlabilmek i9in gereken dart bileJen farlandabk, motivasyon, teknik eri#m ve yetkinlikdir.
Parallel data reduction techniques for big datasets
(2013) Özdoğan, Cem; Özdoğan, Cem; Watson, Dan; 40569
Data reduction is perhaps the most critical component in retrieving information from big data (i.e., petascale-sized data) in many data-mining processes. The central issue of these data reduction techniques is to save time and bandwidth in enabling the user to deal with larger datasets even in minimal resource environments, such as in desktop or small cluster systems. In this chapter, the authors examine the motivations behind why these reduction techniques are important in the analysis of big datasets. Then they present several basic reduction techniques in detail, stressing the advantages and disadvantages of each. The authors also consider signal processing techniques for mining big data by the use of discrete wavelet transformation and server-side data reduction techniques. Lastly, they include a general discussion on parallel algorithms for data reduction, with special emphasis given to parallel waveletbased multi-resolution data reduction techniques on distributed memory systems using MPI and shared memory architectures on GPUs along with a demonstration of the improvement of performance and scalability for one case study.
Temperature and Excitation Intensity Tuned Photoluminescence In Ga0.75In0.25Se Crystals
(Elsevier Science BV, 2013) Işık, M.; Güler, I.; Gasanlyc, N. M.; 101531
Photoluminescence (PL) spectra of Ga0.75In0.25Se layered single crystals have been studied in the wavelength range of 580-670 nm and temperature range of 7-59 K. Two PL emission bands centered at 613 nm (2.02 eV, A-band) and 623 nm (1.99 eV, B-band) were revealed at T = 7K. The excitation laser intensity dependence of the emission bands have been studied in the 0.06-1.40 W cm(-2) range. Radiative transitions from shallow donor levels located at E-A = 0.11 and E-B = 0.15 eV below the bottom of conduction band to single shallow acceptor level located at 0.01 eV above the valence band are suggested to be responsible for the observed A- and B-bands. A simple model was proposed to interpret the recombination processes in Ga0.75In0.25Se single crystals. (c) 2012 Elsevier B.V. All rights reserved.
Calculation of the infrared frequencies as a function oftemperature using the volume data in the ferroelectric phase ofnano2
(Taylor&Francis INC, 2014) Kiracı, Ali; Kiracı, Ali; 42475
We calculate the temperature dependence of the infrared frequencies of the TO and LO modes with the symmetries of A(1), B-1 and B-2 mainly in the ferroelectric phase of NaNO2. This calculation is carried out using the volume dependence of the infrared frequencies through the mode Gruneisen parameter in this crystal. The volume dependences of the infrared frequencies are fitted to the observed frequencies by using constant mode Gruneisen parameter in the ferroelectric phase of NaNO2. Our results show that this method of calculating the infrared frequencies describes the observed behaviour of NaNO2 adequately.
Survey and evaluation on modelling of next-day electricity prices
(2014) Yıldırım, Miray Hanım; Bayrak, Özlem Türker; Weber, Gerhard-Wilhelm; 56416
Optical analysis of TlInS2xSe2(1-x) mixed crystals
(2014) Güler, İpek; 101531
The ellipsometry measurements were carried out on TlInS2xSe2(1-x) mixed crystals in the spectral range of 1.5-6.0 eV at room temperature. The refractive index, extinction coefficient, real and imaginary parts of dielectric function were found as a result of ellipsometric measurements. The energies of interband transitions (critical point energies) of the TlInS2xSe2(1-x) mixed crystals were obtained by means of the second derivative of the real and imaginary parts of dielectric function. The variation of the critical point energies with the isomorphic anion substitution that is sulfur for selenium atoms was established.
Klasik Dönem Osmanlı Şiirinde Patronaj ve Şairin Üretim Süreci İlişkisine Bir Bakış
(2014) Atabağsoy, Naim; 47393
Teacher’s Professional Perception as a Predictor of Teacher – Student Friendship in Facebook: A Scale Development Study
(2015) Akkoyunlu, Buket; Dağhan, Gökhan; Erdem, Mukaddes; 8539
In this study, a scale was developed for providing to make a relation between the tendency and reasons of teachers to add their students as “Friend” on Facebook and their professional perceptions. The study group consists of 158 teachers; 81 of them state that they are “friends” with their students on Facebook and 77 of them state that they are not. The factor structures of the scale were determined through Exploratory Factor Analysis (EFA) and the aforementioned theoretical structure was tested through Confirmatory Factor Analysis (CFA). The results indicate that each sub-scale separates into 4 factors that have an eigenvalue of 1 or above and that they have construct validity and reliability. Depending on the fact that both sub-scales had 4 factors, the aim was to find a common structure among the sub-scales. Regarding the meanings that the related items had, it was found that both sub-scales consisted of sub-factors that could be described as responsibility perception, student perception, professional identity perception and school perception. A secondarylevel confirmatory factor analysis was applied to validate the structures that were determined at the sub-scales and to test whether responsibility perception, student perception, professional identity perception and school perception structures inclined to an upper structure, i.e. teaching perception, or not. The findings indicated that both sub-scales had this hierarchical structure and each model had acceptable goodness-of-fit values. The survey developed a structure that had strong psychometrical features and determined that teachers’ interactions with their students on social networks were related to their professional perceptions.
Global Krizler için Doğrusal Profillere Dayalı Kontrol Şemaları ile Oluşturulan Erken Uyarı Sistemi
(2015) Türker Bayrak, Özlem; Aytaçoğlu, Burcu; Yüksel Haliloğlu, Ebru; 56416
Learning Environments Designed According to Learning Styles and Its Effects on Mathematics Achievement
(2015) Akkoyunlu, Buket; Akkoyunlu, Buket; 8539
Problem Statement: While designing a learning environment it is vital to think about learner characteristics (learning styles, approaches, motivation, interests… etc.) in order to promote effective learning. The learning environment and learning process should be designed not to enable students to learn in the same manner and at the same level, but rather designed by giving thought to students’ existing learning styles. Purpose of the Study: The aim of this study is to examine primary students’ and inspectors’ opinions on different learning environments designed according to students’ learning styles and its effects on students’ achievement. Method: Fifty-five seventh grade students and seven inspectors constituted the research sample. The data were collected through an open-ended questionnaire; a mathematics achievement test and the Pat Wyman Personal Learning Style Inventory were used as data collection tools in the research. Since the group consisted of less than 30 participants, the Wilcoxon Signed Rank Test for Paired Samples was used. Findings and Results: The difference of pre-post test results of visual auditory learners, auditory-kinesthetic learners, and visual-auditory learners are statistically significant. When the ranked average of different grades and their sums are considered, the observed difference is in positive ranking, meaning it is in favor of post-test results. According to these results, different learning environments designed for visualauditory-kinesthetic learners have a positive effect on student grades. The majority of the students stated that the aforementioned activities used in the mathematics lesson could also be used in other school subjects. Conclusions and Recommendations: Student responses emphasized that learning environments should be designed according to student learning styles. Inspectors underlined that learning styles designed according to students’ individual learning styles may increase student success. In addition, inspectors thought that some of the advantages of designing learning environments according to students’ learning styles included an opportunity to learn fairly, an increase in student motivation towards the lesson, and enabling students to learn at their own pace. In the upcoming studies, student behaviors and motivations towards environments designed according to students’ learning styles will be analyzed.

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